Heat Hives: What They Are, What Triggers Them, and How to Find Relief

When your skin breaks out in itchy, red welts after sweating, walking in the sun, or even stepping into a warm room, you might be dealing with heat hives, a type of physical urticaria triggered by rising body temperature. Also known as cholinergic urticaria, this isn’t just a mild irritation—it’s your immune system overreacting to heat, often without any allergen involved. Unlike regular allergies, heat hives don’t come from pollen or food. They show up because your body’s temperature rises—even slightly—and your mast cells release histamine in response. The result? Bumps that burn, itch, and sometimes spread fast.

People who get heat hives often notice them during exercise, hot showers, or even emotional stress that makes them flush. The rash usually appears within minutes and fades within an hour or two once the body cools down. But for some, it happens daily, making workouts, cooking, or even summer days a challenge. It’s not contagious. It’s not caused by poor hygiene. And it’s not just "a rash you’ll grow out of." Studies show it affects up to 1 in 100 people, especially those under 30, and often lasts for years before improving on its own.

What makes heat hives tricky is how often they’re mistaken for other skin issues. A heat rash from blocked sweat glands looks different—it’s tiny red dots, not raised welts. An allergic reaction to something you ate might last longer and include swelling or breathing trouble. Heat hives are specific: triggered by warmth, quick to appear, quick to vanish, and intensely itchy. If you’ve tried antihistamines before and they helped even a little, that’s a strong clue.

There’s no cure, but there are ways to take control. Avoiding sudden temperature spikes helps. Wearing loose, breathable clothes. Cooling down right after exercise. Some people find that taking a non-drowsy antihistamine like loratadine before activity stops outbreaks. Others need to adjust their routines entirely—swimming in cool water instead of running outside, skipping saunas, or using fans indoors. It’s not about avoiding life. It’s about learning how to move through it without triggering your skin’s alarm system.

The posts below cover real strategies people use to manage heat hives, from simple lifestyle tweaks to how certain medications interact with your body’s response to heat. You’ll also find advice on when to see a doctor, how to tell heat hives apart from other rashes, and what supplements or treatments actually have evidence behind them—not just hype. Whether you’ve had this for weeks or years, you’re not alone. And you don’t have to just live with it.